Avantages
It offers a very stable, unique work environment. You may pick up new skills and learn some interesting things while there, since the process is quite foreign to an experienced worker, and being asked to adapt to "the MathWorks way" will challenge you to either learn new skills or do things very differently than you've done previously. It will stretch your repertoire. Health benefits are great, and there are some nice perks that demonstrate the company cares about taking care of their employees, and generally treating people well. It is also a great company for new graduates, and gives a lot of people a fantastic start in their careers.
Inconvénients
The company has A LOT of process (new & untried that needs refinement; legacy; and genuinely great stuff), and is extremely structured. If you like working in an environment that is flexible, adaptive, and has a less formal approach... you will find this much like pushing a boulder up a cliff, or allowing it to roll over you. One of the mindsets is, "we've been there, done that, and whatever new ideas you may have-- they've already been tried." Getting past this mindset is nearly impossible. If you do get past it, chances are you will have proposed a new process, whether that was your goal or not. For these reasons, it is a great place for those who come to the company to be trained by and shaped in the unique process and methodologies they have instated at MathWorks.